PATCH: Support LD_AS_NEEDED

[Paul Brook]

> I don't see there is a big difference here as far as gcc is
> concerned. If we ran into any linker problems, we can always
> ask users to provide their LD_XXXs.  Today we have
>
> emultempl/elf32.em:	      lib_path = (const char *) getenv ("LD_RUN_PATH");
> emultempl/elf32.em:	  lib_path = (const char *) getenv ("LD_LIBRARY_PATH");
>...
> I don't recall any of those have caused any serious issues for
> linker debugging.

I've been bitten by LD_{RUN,LIBRARY}_PATH several times.

Paul